Cassava starch and its usesContents -Previous - NextThe flour produced from the cassava plant, which on account of its low content of noncarbohydrate constituents might well be called a starch, is known in world trade astapioca flour. It is used directly, made into a group of baked or gelatinized products or manufactured into glucose, dextrins and other products.Starchy foods have always been one of the staples of the human diet. They are mostly consumed in starch-bearing plants or in foods to which commercial starch or its derivatives have been added. The first starch was probably obtained from wheat by the gyptians for food and for binding fibres to make papyrus paper as early as !"""-#$"" %.&.Starches are now made in many countries from many different starchy raw materials, such as wheat, barley, maize, rice, white or sweet potatoes, cassava, sago palm and waxy xaize. 'lthbugh they have similar chemical reactions and are usually interchangeable, starches from different sources have different granular structures which affect their physical properties.Starch and starch products are used in many food and nonfood industries and as chemical raw materials for many other purposes, as in plastics and the tanning of leather. (onfood use of starches - such as coating, sizings and adhesives - accounts forabout )$ percent of the output of the commercial starch industry.In many industrial applications, there is competition not only among starches from various sources but also between starches and many other products. *esin glue has largely replaced starch in plywood because of its greater resistance to moisture+ resin finishes are used in the textile industry and natural gums compete with starches in paper making. (evertheless, the continuous development of new products has enabledthe starch industry to continue its expansion. The growth of the starch industry in the future appears to be very promising, providing the ,uality of products and the development of new products permit them to compete with the various substitutes.-../ I(/0ST*ISThe food industries are one of the largest consumers of starch and starch products. In addition, large ,uantities of starch are sold in the form of products sold in small packages for household cooking. &assava, sago and other tropical starches were extensively used for food prior to the Second 1orld 1ar, but their volume declined owing to the disruption of world trade caused by the war. 'ttempts were made to develop waxy maize as a replacement for normal noncereal starches+ but the production of cassava starch has increased considerably in recent years.0nmodified starch, modified starch and glucose are used in the food industry for one or more of the following purposes23a4 directly as cooked starch food, custard and other forms+3b4 thickener using the paste properties of starch 3soups, baby foods, sauces and gravies, etc.4+3c4 filler contributing to the solid content of soups, pills and tablets and other pharmaceutical products, fee cream, etc.+3d4 binder, to consolidate the mass and prevent it from drying out during cooking 3sausages and processed meats4+3e4 stabilizer, owing to the high water-holding capacity of starch 3e.g., in fee cream4.Bakery products'lthough starch is the ma5or constituent of flours, the art of6 bread baking depends to a large extent on the selection of flour with the proper gluten characteristics. Starch is used in biscuit making, to increase volume and crispness. In 7alaysia, cassava starch is used in sweetened and unsweetened biscuits and in cream sandwiches at the rate of $-8" percent in order to soften zyestexture. add taste and render the biscuit nonstickv. The use of dextrose in some kinds of yeast-raised bread and bakery products has certain advantages as it is readily available lo the yeast and the resulting fermentation is ,uick and complete. It also imparts a golden brown colour to the crust and permits longer conservation.ConfectioneriesIn addition to the widespread use of dextrose and glucose syrup as sweetening agents in confectioneries. starch and modified starches are also used in the manufacture of many types of candies such as 5ellybeans. toffee. hard and soft gums, boiled sweets 3hard candy4. fondants and Turkish delight. In confectioneries. starch is used principally in the manufacture of gums. pastes and other types of sweets as an ingredient, in the making of moulds or for dusting sweets to prevent them from sticking together. /extrose prevents crystallization in boiled sweets and reduces hvdroscopicity in the finished product.Canned fruits, jams and prederves*ecent advances in these industries include the partial replacement of sucrose by dextrose or sulfur-dioxide-free glucose syrup. This helps to maintain the desired percentage of solids in the products without giving excessive sweetness, thereby emphasizing the natural flavour of the fruit. The tendency toward crystallization of sugars is also decreased.Monosodium glutamate (MSG)This product is used extensively in many parts of the world in powder or crystal form as a flavouring agent in foods such as meats, vegetables, sauces and gravies. &assava starch and molasses are the ma5or raw materials used in the manufacture of 7S9 in the -ar ast and :atin 'merican countries. The starch is usually hydrolyzed into glucose by boiling with hydrochloric or sulfuric acid solutions in closed converters under pressure. The glucose is filtered and converted into glutamic acid by bacterial fermentation. The resulting glutamic acid is refined, filtered and treated with caustic soda to produce monosodium glutamate, which is then centrifuged and dried in drum driers. The finished product is usually at least ;; percent pure.The production of commercial caramel&aramel as a colouring agent for food, confectionery and li,uor is extensively made of glucose rather than sucrose because of its lower cost. If invert sugar, dextrose or glucose is heated alone, a material is formed that is used for flavouring purposes+ but if heated in the presence of certain catalysts, the coloration is greatly heightened, and the darker brown products formed can be used to colour many foodstuffs and beverages.0niform and controlled heating with uniform agitation is necessary to carry the caramellization to the point where all the sugar has been destroyed without liberating the carbon.T< 9:0&.S I(/0ST*='ccording to 1histler and >aschell, 'bu 7ansur, an 'rabian teacher and pharmacologist, about ;)$ './. described the conversion of starch with saliva into an artificial honey. In 8?88 @irchoff discovered that sugar could be produced by the acid hydrolysis of starch. 9lucose, or dextrose sugar, is found in nature in sweet fruits suchas grapes and in honey. It is less sweet than sucrose 3cane or beet sugar4 and also less soluble in water+ however, when used in combination with sucrose, the resulting sweetness is often greater than expected.The commercial manufacture of glucose sugars from starch began during the (apoleonic 1ars with ngland, when suppliers of sucrose sugar were cut off from -rance by sea blockade. *apid progress was made in its production in the 0nited States about the middle of the nineteenth century.'t present, glucose is usually produced as a syrup or as a solid. The physical properties of the syrup vary with the dextrose e,uivalent 3/4 and the method of manufacture. /extrose e,uivalent is the total reducing sugars expressed as dextrose and calculated as a percentage of the total dry substance. 9lucose is the common name for the syrup and dextrose for the solid sugar. /extrose, sometimes called grape sugar, is the /-glucose produced by the complete hydrolysis of starch.Starch hydrolysisTwo methods for starch hydrolysis are used today for the commercial production of glucose2 acid hydrolysis and partial acid hydrolysis followed by an enzyme conversion.'cidification is the conversion of starch into glucose sugar by acid hydrolysis. This operation is carried out in batches or a continuous process. In the first process, the starch slurry, A"-A8B%e, is mixed with hydrochloric acid 3sulfuric acid is sometimes used4 to bring the p< to around 8.?-A." in a steam converter and heated to about 8C"B& until the desired / is reached. The continuous process, which is replacing the batch process, involves feeding the mixture of starch slurry and hydrochloric acid intoa tubular heat-exchanger. The time and temperature of the process are ad5usted to the desired / in the end product.In the next step, neutralization, the acidified mixture is neutralized with sodium carbonate or soda ash to remove the free acid and bring the p< value to $." ).". Sodium chloride is formed in the syrup in small ,uantities as a result of the neutralization of the hydrochloric acid by the sodium carbonate and remains in solution.*efining follows. Some solids - impurities, precipitated protein and coagulated fat - can be removed by centrifugal separation. Impurities will depend largely on the starchused and its purity. The solution is then passed through filters 3filter presses or candle-type ceramic filters4.The clear brown filtrate is decolourized by passing it through tanks of activated carbon, which removes colours and other impurities from the solution by surface adsorption but has no effect on the sugar.*efining can be done by ion-change resins instead of activated carbon or combined with it. ' recent development is to refine the converted li,uor by electrodialysis, and the final glucose syrup is very superior.&oncentration is the final step. The refined syrup is concentrated under vacuum in batch converters or continuous heat exchangers until the concentrated syrup reaches ?"-?$ percent solids or !# !$B%D. &ommercial glucose syrups are sold according to the %eaumD standard, which is a measure of the dry substance content and specific gravity.9lucose syrup is transported in drums or in bulk road or rail tanks. It should not be stored in large ,uantities for long periods of time because its colour may deteriorate.In the acid-enzyme process the starch slurry is treated by acidification, neutralization and filtration as in the acid hydrolysis process and then is fed into the enzyme converter. The temperature and p< are ad5usted to the optimum conditions and the enzyme is added with slow agitation. The time of conversion depends on the initial dextrose e,uivalent obtained by acid hydrolysis, the type and strength of the enzyme and the final / re,uired. 'fter the conversion has been completed, the enzyme is rendered inactive by raising the temperature and ad5usting the process, adopted in 8;C8, is used to produce the highest proportion of all the bread consumed in the 0nited @ingdom.xperiments carried out by the %ritish 'rkady &o. :td., using mechanical leavening rather than bulk fermentation for the ripening of the dough and a blend of C" percent wheat flour, #" percent cassava starch and 8" percent soybean flour, produced a bread of good ,uality almost e,ual to the normal wheat-flour bread in volume, appearance and eating ,uality.Several -'.-operated 0(/>GS- pro5ects concerned with the use of composite flours in bread-making have been realized. %akery products made from composite flours of wheat 3at least )$ percent4 and potato, maize and cassava have been developed by an experimental bakery in &ampinas, State of SHo >aulo, %razil. 3.ther pro5ects involving the use of flours other than cassava flour in bakery products have been carried out in (iger, Senegal and Sudan.4 The report of a 5oint -'.G0(/> mission in &olombia recommended the establishment of an experimental bakery to determine thesuitability of locally available raw materials for the production of bakery products from composite flours 3e.g., cassavaGsoybean4. The pro5ect was executed with -'. participation under a bilateral agreement between &olombia and the (etherlands.(0T*ITI.(': F':0 .- &.7>.SIT -:.0*SThe nutritional value of bakery products made from composite flours was assessed in 8;C$ by the &entral Institute for (utrition and -ood *esearch, 30trecht, Ieist4, where the nutritional value of cassavaGsoya bread and cassavaGgroundnut bread was compared with the protein ,uality of common wheat bread. It was concluded that the protein ,uality of both breads was higher than that of common wheat bread. The cassavaGsoya bread topped the other two breads in protein ,uality, while the cassavaGgroundnut bread was slightly superior to common wheat bread.In 8;C; at the Jueen lizabeth &ollege, :ondon, breads produced at the %ritish 'rkady &o. :td. were assessed. They were made from various composite flour mixtures consisting of wheat flour, cassava starch, soya flour, millet and sorghum flour and fish-protein concentrate in various proportions with mechanical leavening. *esults indicated that the protein value of the original bread had not been impaired by supplementation, but showed improvement.>rospects for commercial production and widespread consumption of bread made of composite flours in different countries will depend upon local acceptance 3taste and characteristics of the bread4 and the price at which the bread will be available to the public.-ood habits are primarily based on socioeconomic and other conditions rather than on scientific considerations. &hanges in established habits can take place gradually through public education and the spread of knowledge.Cassava in animal feed&assava is widely used in most tropical areas for feeding pigs, cattle, sheep and poultry. /ried peels of cassava roots are fed to sheep and goats, and raw or boiled roots are mixed into a mash with protein concentrates such as maize, sorghum, groundnut or oil-palm kernel meals and mineral salts for livestock feeding.In many tropical regions, the leaves and stems of the cassava plant are considered a waste product.